The present invention relates to a shock absorber using a honeycomb block, and more specifically to a shock absorber wherein the degree of freedom of honeycomb design is improved.
It is a known fact that shock absorbers each of which comprises a lamination of plural honeycomb blocks are used as crash test members or shock absorbing members for automobiles. When such a shock absorber comprising honeycomb blocks is used in a crash test for an automobile, it is necessary that the shock absorbing characteristic satisfies requirements specified by laws and regulations. Namely, in the shock absorbing characteristics, it is assumed that the front of an automobile has a certain quantity of rigidity, which causes the load to rise with increasing amount of deformation. Furthermore, the upper and lower limits of the load corresponding to an arbitrary amount of deformation are established, and it is required that the load should not exceed said limits.
A shock absorber according to prior art using honeycomb blocks is constructed, as shown in FIG. 9 for example, such that plural honeycomb blocks 1 comprising a cell opening 1a at the front and at the rear is laminated by inserting in-between intermediate plates 2 each of which consists of a metallic plate or the like. In the case of this shock absorber, the strength of each honeycomb block 1 is changed in stages for the purpose of adjusting the shock absorbing characteristics (reaction force characteristics). In each of said intermediate plates 2, a large number of vent holes 3 are formed to ensure ventilation between the interior and the exterior of the honeycomb block 1. Moreover, besides the above, a shock absorber wherein intermediate plates 2a having no vent holes 3 are inserted in-between as shown in FIG. 10 is also known.
However, in the case of the shock absorber described above wherein plural honeycomb blocks 1 are laminated, the load increases in stages with respect to the displacement of the shock absorber as shown in FIG. 11, since the strength varies abruptly between adjacent honeycomb blocks, and therefore it has been difficult to moderate the load variation. Moreover, if the length of each honeycomb block is reduced and the number of laminated honeycomb blocks 1 is increased for the purpose of moderating the variation of strength between adjacent honeycomb blocks, a problem has been encountered in that the construction of the shock absorber becomes more complicated.
The object of the present invention is to provide a shock absorber wherein it is possible to design arbitrary shock absorbing characteristics in spite of the fact that the construction is simple.
The shock absorber of the present invention for achieving the object comprises a honeycomb block with plural cylindrical cells arranged in parallel, wherein the strength of the honeycomb block to withstand a load in the cell axial direction is adjusted by a processed configuration of the cells.
Since the strength of the honeycomb block to withstand the load in the cell axial direction is adjusted by the processed configuration of the cells, it is possible to design arbitrary shock absorbing characteristics in spite of the fact that the construction is simple. Particularly, if the strength of the honeycomb block to withstand the load in the cell axial direction is gradually reduced from one axial end of each cell to the other axial end, and if the shock load is designed to be applied from the other end of said honeycomb block, the load rises with increasing amount of deformation of the shock absorber, thereby easily realizing the shock absorbing characteristics which correspond to the rigidity of the front of an automobile.
A thinning process, a metallic plating process or a punching process can be utilized as the method of processing of the cell. Particularly, when a combination of a punching process, and one of a thinning process and a metallic plating process is utilized, it is possible to arrange a desired shock absorbing characteristics with accuracy. The thinning process is a process in which the thickness of each sidewall of the cell is reduced, thereby making it possible to adjust the strength of the honeycomb block to withstand the load in the cell axial direction, on the basis of the sidewall thickness of said cell. The metallic plating process is a process in which a metallic plating layer is provided on each sidewall of the cell, thereby making it possible to adjust the strength of the honeycomb block to withstand the load in the cell axial direction, on the basis of the thickness of the metallic plating layer. The punching process is a process in which plural through holes are provided in each sidewall of the cell, thereby making it possible to adjust the strength of the honeycomb block to withstand the load in the cell axial direction, on the basis of at least one factor chosen from among the density, the arrangement, the size, and the shape of the through holes.
In the case of adjusting the strength by means of through holes, it becomes possible to establish more moderate strength variation along the cell axis if a plurality of hole rows each of which comprises plural through holes arranged axially in the sidewall of the cell is provided, and if any arbitrary through hole in an arbitrary hole row is positioned between a pair of adjacent through holes along the cell axis in another hole row. Particularly, it is good practice to arrange plural through holes such that any arbitrary plane perpendicular to the cell axis passes through at least one through hole.